The invention relates to an anode disc for a rotary-anode X-ray tube, comprising a supporting body which can be connected to a shaft and which is connected to a ring of pyrographite which is concentric with an axis about which the disc is adapted to be rotated in operation and whose surfaces of higher thermal conductivity extend at least approximately perpendicularly with respect to the focal path connected thereto.
An anode disc of this kind is known from German Offenlegungsschrift 24 40 988. Therein, the graphite supporting body of the anode disc comprises a groove in which the pyrographite ring is inserted. The heat developed in the focal path provided on the outer edge of the pyrographite ring is dissipated better by this pyrographite ring than if the anode body were to consist exclusively of (electro) graphite.
Heat developed in the focal path is then conducted inwards towards the axis of the supporting body, because the surfaces of higher thermal and electrical conductivity which extend perpendicularly to the growth direction of the pyrographite are situated perpendicularly to the axis of the graphite body of the rotary anode. Consequently, the bearings of the shaft whereto the anode disc is connected inside an X-ray tube are liable to be thermally overloaded.